Question: 8 markers cost $15.36. Which equation would help determine the cost of 14 markers?
Answer: There are several equations that could help determine the cost, each with a slightly different approach. Let $x$ represent the unknown cost of 14 markers. Since 14 markers cost $x$ , we have the following proportion: $\dfrac{14}{x}$ We can write the fact that 8 markers cost $15.36 as a proportion: $\dfrac{8}{\$15.36}$ The cost changes along with the number of markers purchased, and so the two proportions are equivalent. $\dfrac{14}{x} = \dfrac{8}{\$15.36}$